Brake actuating mechanism



Jane. 2o, 1939.

B. DICK 'BRAKE ACTUATING MECHANISM Filed Jan. 25,- 1937 2 sheets-sheet 1I IO,

INVENTOR BURNS DICK ATTORNEY June 20, 1939. B1 DICK BRAKE .A cruAT'INcrMECHANISM Filed Jan. 25, 1931 2 sheets-sheet, 2

IN VEN TOR BURNS DICK ATTORNEY/ 2o duce an eilicient, compact, andeconomical actu- Patentecl June 20, 1939 narran sTATEs PATENT oFFIcEenana sername. MxscnANrsM4` Burns Dick, Ferguson, Mo., assignor toWagner Electric Corporation, St. Louis, Mo., a corporation of vDelawareMy invention relates to brakes and more particularly to mechanism formoving the friction element thereof inte cooperative engagement-withAthe rotatable element.

One of the objects of in y invention is to construct a-brake actuatingmechanism that is particularly adapted to be associated with a brakehaving a relatively wide brake shoe or brake band.

Another object of my invention is to provide a pair of wedge or cammeans which may be simultaneously operated with equal force to actuate abrake. l

Still a-further and more specific object of my invention is to providetwo wedge elements for expanding the adjacent ends-of either apair ofbrake shoes or a brake band and an associated oating iluidy motor formoving said wedges in opposite directions and with equal force.

Still another object of my invention is to 'proating mechanism of thefluid pressure type.

Other objects of my invention will become apparent from the followingdescription taken in connection with the accompanying drawings showingseveral embodiments thereof.

In the drawings Figure l is a View of a vehicle axle showing my brakeactuating mechanism associated with the brake assemblies at each end;Figure 1A is a side view of a brake assembly; Figure 2 is an elevationof one of the actuating fluid motors and associated wedges; Figure 3- isa cross-sectional View of the structure of Figure 2 showing it inoperative position with respect to the friction device orbrake shoes;Figure 4 isa cross-sectional view of a modied construction showing itassociated with the brake shoes; and

Figure 5 is an elevation of the modiiled construction.

Referring to Figures l, 2, and 3, I have shown my novel brake actuatingmechanism associated with the rear axle of a motor vehicle in which abrake assembly is employed at each end thereof in association with theusual wheels but it is to be understood that this is by way of exampleonly as the mechanism may be employed whenever it is desired to actuatethe friction device of any brake assembly. Reference character iindicates the rear axle housing of the vehicle, and positioned at eachend thereof is a brake assembly 2 comprising a brake drum 3, a backingplate d, and a pair of brake shoes 5 and 6 for cooperation with the drumin a well llrnown manner. The drum -3 is adapted to be attached to avehicle wheel (not shown) for rotation therewith and and positioned forreciprocation in this cylinder backing plate 2, which encloses the openside of the drum, is rigidly secured to the axle housing.

My novel brake actuating mechanism is associated with each brakeassemblyland since these are duplicates, only one will be described indetail. 5 The end of brake shoe 5 has pivotally mounted thereon spacedrollers l and 8 and the adjacent end of brake shoe 6 has pivotallymounted thereon similar spaced rollers 9 and I0, lrollers 1 and 9 beingopposed to each other and rollers B and I0 i6 being opposed to eachother in the manner shown.

vA tubular member II extends through an enlarged opening I2 in backingplate ll and has its inner end positioned between the adjacent ends ofthe brake shoes. The opposite sides ofthe inner l5 end of this tubularmember is provided with slots I3 and i4, slot I3 having a portion ofrollers -i and 8 received therein, and slot I4 having a portion ofrollers 9 and Ill received therein. The ex- 4rollers and to each otherthat when they are moved toward each other, they will move shoes 5 and 6in opposite directions and engage these shoes with the inner surface ofthe brake drum.

The structure employed for moving wedges I5 and I1 toward each othercomprises a fluid motor of the cylinder and piston type which isoperable bya suitable fluid under pressure. The specific constructionshown involves a cylinder I8-con nected tothe outer end of the tubularmember by. means of a threaded attaching element I9,

46 is a piston20 mounted upon the end of rod- I6 which is of suchlengthas to project Within the cylinder. The extreme outer end of cylinder I8is closed with the exception of a passageway 2l for placing the cylinderin commnication with a iluid supply conduit 22. The piston 20 hasassociated therewith a suitable packing element 23 for preventingleakage of fluid past the piston and a spring 24 for returning thepiston to itsnormal position when the fluid pressure is released fromthe working chamber of the cylinder and piston combination.i The rod I6and tubular member II also have associated therewith a suitable ilexibleboot 25, one end of which is secured tol tubular member II and the otherend to rod le in order that dust and dirt may be excluded from theinterior of the cylinder. There is also a flexible boot 26 interposedbetween the tubular element and the backing plate in order that dust anddirt may be prevented from entering the brake assembly through theenlarged opening l2 in the backing plate.

The cylinder and piston combination is suspended for free movement by asupport 21 mounted upon axle housing l This support carries rollers orspools 2t forming a rolling support for the cylinder, the upper rolleror spool being mounted in spaced.` relation to the lower roller or spoolby an upstanding bracket 21 (shown in dashed lines). The conduits 22leading from each of the cylinders of the iiuid motors areinterconnected by a suitable conduit 2d and this conduit, in turn, isconnected to another conduit 3G leading from the source of pressurewhich may be either compressed air or a hydraulic compressor dependingupon the type of uid employed.

Referring to the operation oi my improved brake actuating mechanism,when it is desired to apply the brakes, fluid under pressure is admittedto the working chamber of the cylinder and piston combination and, as aresult thereof, cylinder IB will be moved to the le'ft carrying with ittubular member il and wedge-l, and piston 2li will be moved to the rightcarrying with it rod I6 and wedge l1. This action results in wedges i5and l1 being moved toward each other with an equal pressure due to thecylinder and piston being floatingly mounted on support 21 and wthismovement of the wedges will' move brake ted projections on wedge 31.

shoes 5 and E outwardly and place them in engagement with the drum, thusbringing about the desired braking action. The brake shoes 5 and 6 arefree to move as a unit in order to properly set themselves on the drum,this movement being permitted by the enlarged opening I2 in the backingplate which allows free lateral movement of tubular member H. When theuid pressure is released in the cylinder, the retractile spring 5l ofthe brake shoes will return the wedges, the cylinder, andthe piston totheir normally inoperative positions.

Referring to Figures i and 5, AI have s hown the actuating i cylinderand piston combination mounted within the drum and between the twooperating` wedges. In this construction the end of brake shoe 3l haspivotally mounted thereon grooved rollers 32 and 33, and the end ofbrake shoe 34 has pivotally mounted thereon grooved rollers 35 and 3G.An operating wedge 31 is adapted to cooperate with rollers 32 and 35,and an operating wedge 38 is adapted to cooperate Swith rollers 33 and3B, both wedges being positioned in the grooves of the rollers wherebythe entire mechanism may be properly supported. The wedge 38 has weldedthereto the closed end of cylinder 39, the open end thereof beinginterengaged for sliding movement with suitable slot- A piston 4I isslidably mounted on the cylinder and secured thereto is a piston rod 42which extends through a suitable opening in an enlarged portion of wedge31 and to a point exterior of the brake assembly. This piston hasassociated therewith a packing 43 for preventing leakage and a spring 44for maintaining the piston and cylinder in their normal positions. Thepiston rod 42 is formed with a passageway .45 ior placing the working,end of the cylinder in'communication with the supply conduit 46 attachedto the outer end of the piston rod. The piston rod also is provided witha suitable abutment" d1, shown as an adjustable nut, cooperating withwedge 31 in order that the (movement of the piston may be transferred tothis wedge. The backing plate d8 of the brake assembly has an enlargedopening i9 through which piston rod 62 extends and this opening isclosed by a suitable flexible boot 50.

In the operation of this modified construction, when it is desired tomove the brake shoes into l engagement with the drum, uid under pressureis forced into the Working end of the cylinder and piston combinationand, as a result thereof, cylinder 39 will be moved to the rightcarrying with it wedge 38, yand piston di will be moved to the leftcarrying with it, by means of abutment lil, wedge 31. `The movement ofwedges 31 and 38 in opposite directions results in the brake shoes beingmoved apart, thus applying the brakes. Due to the noating action of thecylinder and piston combination, the pressure exerted upon the shoes byeach of the wedges is equal and, therefore,

each wedge will tend to expand the portions of the brake shoes it actsupon with an equal force. The interengaging relation between wedge 31and the cylinder permits free movement of these two members andmaintains them in alignment. When the pressure is released in theworking chamber, the retractile spring of the brake shoes (not shown)willreturn the wedges, the cylinder, and the piston to their normallyinoperative positions.

Bothv brake actuating mechanisms just described have been found to beparticularly well adapted for solving the problems present in properlyactuating small diameter brakes for heavy vehicles wherein relativelywide brake shoes are employed. The wedges apply equal pressure to eachside of each shoe and because of this, there is no tendency of the edgesof the shoes being bent away from the drum as would 'oe the case ln theusual construction. wherein a single cylinder and piston combination isemployed which is positioned in the same plane as the brake" shoes andapplies pressure to the centers of the ends of the shoes. Also by usingtwo Wedges and a floating cylinder and piston combination the entireconstruction is in balance and there is no necessity for the provisionof a fixed support to take any reaction as the reaction of one wedge isimmediately transferred to the other, -Because of the floatingsuspension of the wedg'es and the iluid motor, the vshoes are able toaccommodate themselves very readily to the -varying contours of thebrake drum and the bellmouthing of the drum due to thev heat generatedduring braking. The positioning of the actuating mechanism between theends of the shoes also eliminates the problem of providingA suflicientroom to mount the actuating mechanism in the drum below the shoe endswhich is present when small diameter brakes are employed. It is also tobe noted that the construction shown in Fig- 'ures 1,2 and 3 is such asto place the cylinder and piston combination exterior of the drum,thereby permitting a better cooling action and less possibility of theheat generated during braking aiecting the iluid actuating mechanism andthe liquid therein in the event a liquid is employed.

Being aware of the possibility `of modifications in the particularstructure herein described without departing ,from .the fundamentalprinciples of my invention, I do-not intend that its .scope be huntedexcept as set forth by the ap pended claims. l

.friction device having a free end and adapted .scoping relation, one ofsaid rods being connected 5 vand which act on the end of the frictiondevice wedge, and a fluid motor having elements movlto control thebraking action thereof with the aligned wedges oooh adapted to cooperatewith drum. 8nd means 1'01' Simultaneuiy moving Said the said adjacentends, and means carried by the 25 n verse to the plane of the frictiondevice to thereby for moving said wedges in opposite directions tothedrum. the forces produced by sindv wedges deviee'into engagement withthe drum, the forces .vite in .the axial dire'ctiOn 0f Said frictiondevice ends of the friction devicein theaxiei direction being balancedyof said friction device being balanced.

' the forces. produced by said wedges and` which snm wedges' and mem forsupplying fluid under baineed- 10. In braking apparatus, a rotatabledrum,y a 45 i friction device adapted to" cooperate with a single drumono hovig o free end, two aligned wedges *iriotioo device 'beingbalanceo f rollers carriedv by eachl free end, the rollers on f. motor`exteriorfof the drumand friction device and piston mounted inthecylinderyand connected to 65 comprising two'A elements movable inopposite disaid other wedg and means for supplying uid Having fullydescribed my invention, what I 6. In'braking apparatus,v a rotatabledrum, a claim as new and desire to secure by Letters Patfriction deviceadapted lto cooperate with. the ent of the United States is: drum, twoaligned wedges each cooperating with' 1. In braking apparatus, arotatable drum,. ii.v a portion of the friction device, two rods inteleto be moved into engagement with a single zone to one of the wedgesand the other rod to the of the drum, two wedges having opposed inclinedother wedge, and means for simultaneously movsurfaces for cooperationwith spaced portionsof ing said rods in opposite' directions to therebysaid free end -of .the friction device to thereby move the wedges inopposite directions to. actuate actuate the friction device intoengagement with the friction device. f f the drum vandpermit. itsdisengagement to pro- 7. In braking apparatus. aV rotatable drum, a ducea controlledbraking action, and nuid-operfriction device adapted to`cooperate with the ated means for simultaneously moving said drum, twoaligned wedges each cooperating with wedges in opposite directions withequal forces a portion of the friction device. two rods in teleand in aplane transverse to the plane of the fricscopingn'elation, one of saidrods connected lto 15 tion device. the forces' produced by said Wedgesone o;l the wedges and the other rod to the other in the axial directionof said friction device be-l able in opposite directionsand connected tothe ing balanced. i rods for operating the wedges to thereby actuate 2.-In braking/apparatus, a rotatable drum, a the friction device, 20friction device adapted to cooperate with a single a. 1n brakingapparatus, a' rotatable drum, a zone of the drum. two opposed wedgesooope friction device adaptedtocooperate' with e, single ine withdifferent portions 0f the friiiiOn devi zone of the drum and havingadjacent ends, two

Wedges in opposite direetins in 8 Plane tlenfriction device andinterposed between thewed'ges move said friction device intoengagementwith thm-wy` move som odjooent ends of the friction and which act on theportions of the friction deproduced by said wedges and which act on the80 3. In braking apparatus. a rotatable drumie 9. 1n braking apparatus.a rotatable drum, a friction device adapted. to cooperate with a singlemotion dem adopted to cooperate with the 2013 0f the drum. 10019D0866Wedges COOPeltin dru'm and having adiacent ends, two aligned a5withdifferent portions o f the friction device, andwedges enen adoptedto cooperate with the said means comprising a fluid motor forsimultaneousadjacent ends, n fluid motor comprising o piston 1y movingsaid wedges. with equal fmes' and in and cylinder interposed between thewedges and opposite directions in e' Plone transverse. to' the .carriedbythe friction device, a connection beplane'of the friction device tothereby move said tween the piston'4 and one of Said wedges, o con- .-40friction device into engagement ywith the drinn, neet-,ion between theoynder and the other of act on the of the friction m the i pressure tothe cylinder to move the axial direction of said friction device beingWunder and pistn in opposite directions,

4. In braking apparatus. a rtatble drum. a' friction device adapted tocooperate with the ne of the drum and having adiaoenteods vwo Writingwith spaced portions of said free opposed Wedges eeoh adapted vooooperaiewlthl end, a piston connected to one wedge, a cylinthe adjacentends to control the braking action of der connected to the other wedge.said piston 5o the friction device' and means for simultaneouslybeingreciprocable in the cylinder and bothbeng moving Said Wedges inopposite directions in e intei'posedfbetween the wedges, and means forplane transverse to the plane o f the frictionsupplying mnd underpressure to the cylinder to device to thereby move said adjacent eods mthereby move the cylinder and piston in opposite opposite directionstocause the. friction jdevice maant l 55 to ooopere'te with the drumthe' forces Piodooed ll. In braking apparatus a rotatable drum, a bySeid Wedges and which et on the ends of' friction device `adapted' tocooperate with the the motion device m the axial direcvion of said drumand having adjacent free ends.'two grooved 5- im braking apparatus erotatable e one end being opposite the rollers on'the adjacent 60motion. device adapted to Cooperate the end, two aligned wedges each ofwhich cooper-- drum and having e'd-ia'oeni" ends' two Y'ugned ates withthe groove of a roller on each end of wedges each adapted to ooopei'ateWiiiiihe odio" .the friction device, a cylinder secured to one cent endsof the friction device, a floating iiuid wedge and sndanlyengaging' theother Wedge, o,

rections, and connecting means between the eleunder pressure to thecylinder -to thereby move ments andthe wedges whereby the wedges willthe cylinder and piston in opposite directions.

be moved in oppomte directions and with an equal pressure when the fluidis operated. l. .A f BURNS DICK. v. 70

